The building codes in many localities require the use of firebreaks in the construction of buildings so as to prevent or hinder the spreading of fire from one floor to another floor or one room on a level to another room on the same level. In present practice, when a conduit, such as one used for carrying electric cable, passes from one floor to another floor through a ceiling, the area surrounding the opening through which the conduit passes is filled with a thermal barrier material to function as a firebreak. However, the conduit itself is usually formed from metal and has a relatively high thermal conductivity. Therefore, if a fire breaks out on one floor, the conduit on that floor heats up to a high temperature and conducts a high percentage of that heat to the next adjacent portion of the conduit in the next adjacent floor. If there are flammable materials close to the portion of the conduit to which the heat has been conducted, then there is a good possibility that the flammable material would be ignited and propagage the fire.